We report numerical and analytical studies of the reversal of the magnetic moment of a single- domain magnetic particle by a circularly polarized ac field of time-dependent frequency. For the time-linear frequency sweep, the phase diagrams are computed that illustrate the dependence of the reversal on the frequency sweep rate v , the amplitude of the ac field h , the magnetic anisotropy field d , and the damping parameter . It is shown that the most efficient magnetization reversal requires a non-linear time dependence of the frequency, ! ( t ) , for which an exact analytical formula is derived with account of damping. The necessary condition of the reversal is h > d . Implementation of a small-scale magnetization reversal is proposed in which a nanomagnet is electromagnetically coupled to two weak superconducting links controlled by the voltage. Dynamics of such a system is analyzed with account of the back effect of the magnet on the superconducting links.
Cai, Liufei; Garanin, Dmitry A.; and Chudnovsky, Eugene M., "Reversal of magnetization of a single-domain magnetic particle by the ac field of time-dependent frequency" (2013). CUNY Academic Works.